Some Questions And Answers About VC8 Charger

Here collect some questions about the VC8 charger from XTAR customers. 

Why does the battery voltage not show 4.2V after the lithium-ion battery is fully charged?
The charging cut-off voltage accuracy of the lithium-ion battery of the VC8 charger is ±1%, that is, the battery voltage display range after charging is 4.16~4.24V. However, the charge cut-off voltage is also affected by the internal resistance value. The higher the internal resistance value, the lower the charge cut-off voltage, and sometimes the cut-off voltage lower than 4.16V is also a normal phenomenon. (Ni-MH battery is the same)

Why does the battery show different voltage in different modes (the charging mode - grading mode - store mode)?
The calculation formula of the real-time voltage is as follows: real-time voltage = true voltage + resistance x current. Under normal circumstances, switching from the normal charging mode to the grading mode, and then switching to the store mode, the charging current will also change accordingly, resulting in a corresponding change in the real-time voltage, which is a normal phenomenon. (In the grading mode, the current in the charging phase is the same as the current in the normal charging mode, and the discharge current is fixed at 300 mA; in the store mode, the current is fixed to 300 mA whether charging or discharging);

Why does the battery's charging current not reach 3A?
The battery charging current reaches 3A with the following five conditions:
1. The battery must be placed in channel 1 or channel 8;
2. The QC3.0 adapter and the data cable carrying the corresponding protocol must be used;
3. The manual current must be adjusted to 3A;
4. The internal resistance of the battery must be less than 40mΩ;
5. The battery must be in the constant current charging phase;
Note 1. for the over-discharged battery, the charging current cannot reach 3A in the activated (ie turbulent) charging state;
Note 2. the charging current cannot reach 3A after entering the constant-voltage charging phase.

Why do some batteries display the voltage directly after being placed in it, and there is no detection process of -.--V?
The occurrence of -.--V is actually testing the internal resistance of the battery, but not all the batteries will be tested for internal resistance after being placed in the VC8. In the following two cases, the battery will not be tested for internal resistance of the battery. 

Instead, directly display the battery voltage:
1. For batteries that are close to full charge, it is generally 4.1V or above (there may be some difference depending on the internal resistance value of the battery, the smaller the internal resistance is, the higher the maximum voltage can be tested), and the internal resistance will not be tested to prevent overcharging;
2. If the input adapter is insufficiently powered, the internal resistance will not be tested to prevent the adapter from being overloaded.

Why is the resistance value of the battery different tested in several times?
First of all, the product is tested in the channels of the charger. It is necessary to make sure whether the battery is in good contact with the positive and negative electrodes. If the contact is not good, the internal resistance value will greatly deviate. In addition, the charger tests the internal resistance through the current pulse. When the battery voltage is extremely low, the battery voltage varies greatly, so there is also a large internal resistance. 

The most suitable testing voltage is the platform voltage range of the battery. V~3.8V. And, in order to prevent overcharging after the battery voltage is higher than 4.16V, the test will be interrupted during the internal resistance test, and the display value will deviate in this case.

Why is my battery charge capacity tested lower than the battery's nominal value?
The nominal capacity value of the battery is the capacity value after the lithium battery is discharged to 2.75V with 0.1C - 0.2C and then standard charged with 0.2C. Nowadays, most of the devices that use batteries are set to stop using when the battery voltage reaches 3.0V-3.3V to prevent battery over-discharge, so the battery actually remains 10%~20% power. In this case, the tested charging capacity will definitely be less than the nominal capacity value. If you need to know the battery's more accurate capacity, you can test it in grading mode.

Why is the Ni-MH battery a little hot after being fully charged?
The method is quite special in judging whether the Ni-MH battery is fully charged. It is judged by the change of the negative voltage (-△V) and zero voltage (0△V) of the battery after fully charged. At this stage, the Ni-MH battery no longer stores energy but convert the charged energy into heat by chemical reaction. A good Ni-MH battery can quickly experience negative voltage, but a bad battery will remain in the converting process for a while, so there will be some heat, but this is normal. This phenomenon will not affect battery life.

Some tips for you:
1. The FeLiO4P battery can be charged in the Store mode, and the terminal voltage of the Store mode is substantially the same as the cut-off voltage of the FeLiO4P battery.

2. When charging more than one battery, if you need a battery urgently. You can take out some batteries, and the remaining battery will be charged faster.

For more information about VC8 charger, please click here.